The present invention is directed to vertebrate submucosa-derived collagenous matrices in combination with preselected cell population as tissue graft construct for the use in the repair of damaged or diseased tissues. The collagenous matrices for use in accordance with the present invention comprise highly conserved collagens, glycoproteins, proteoglycans, and glycosaminoglycans in their natural configuration and natural concentration. The extracellular collagenous matrix for use in this invention is derived from submucosal tissue of a warm-blooded vertebrate.
In accordance with the present invention the submucosa is isolated from warm-blooded vertebrate tissues including the alimentary, respiratory, intestinal, urinary or genital tracts of warm-blooded vertebrates. The preparation of intestinal submucosa is described and claimed in U.S. Pat. No. 4,902,508, the disclosure of which is expressly incorporated herein by reference. Urinary bladder submucosa and its preparation is described in U.S. Pat. No. 5,554,389, the disclosure of which is expressly incorporated herein by reference. Stomach submucosa has also been obtained and characterized using similar tissue processing techniques. Such is described in U.S. patent application No. 60/032,683 titled STOMACH SUBMUCOSA DERIVED TISSUE GRAFT, filed on Dec. 10, 1996. Briefly, stomach submucosa is prepared from a segment of stomach in a procedure similar to the preparation of intestinal submucosa. A segment of stomach tissue is first subjected to abrasion using a longitudinal wiping motion to remove the outer layers (particularly the smooth muscle layers) and the luminal portions of the tunica mucosa layers. The resulting submucosa tissue has a thickness of about 100 to about 200 micrometers, and consists primarily (greater than 98%) of acellular, eosinophilic staining (H&E stain) extracellular matrix material.
Preferred submucosal tissues for use in accordance with this invention include intestinal submucosa, stomach submucosa, urinary bladder submucosa, and uterine submucosa. Intestinal submucosal tissue is one preferred starting material, and more particularly intestinal submucosa delaminated from both the tunica muscularis and at least the tunica mucosa of warm-blooded vertebrate intestine.
As a tissue graft, submucosal tissue undergoes remodeling and induces the growth of endogenous tissues upon implantation into a host. It has been used successfully in vascular grafts, urinary bladder and hernia repair, replacement and repair of tendons and ligaments, and dermal grafts. The preparation and use of submucosa as a tissue graft composition is described in U.S. Pat. Nos. 4,902,508; 5,281,422; 5,275,826; 5,554,389; and other related U.S. patents. When used in such applications the graft constructs appear not only to serve as a matrix for the regrowth of the tissues replaced by the graft constructs, but also promote or induce such regrowth of endogenous tissue. Common events to this remodeling process include: widespread and very rapid neovascularization, proliferation of granulation mesenchymal cells, biodegradation/resorption of implanted intestinal submucosal tissue material, and lack of immune rejection. The use of submucosal tissue in sheet form and fluidized forms for inducing the formation of endogenous tissues is described and claimed in U.S. Pat. Nos. 5,281,422 and 5,275,826, the disclosures of which are expressly incorporated herein by reference.
Submucosal tissue can be obtained from various sources, including intestinal tissue harvested from animals raised for meat production, including, for example, pigs, cattle and sheep or other warm-blooded vertebrates. This tissue can be used in either its natural configuration or in a comminuted or partially digested fluidized form. Vertebrate submucosal tissue is a plentiful by-product of commercial meat production operations and is thus a low cost cell growth substrate, especially when the submucosal tissue is used in its native layer sheet configuration.
The submucosa tissue graft constructs prepared in accordance with the present invention are a substantially acellular matrix that provides a superior cell growth substrate resembling the matrix environment found in vivo. The natural composition and configuration of submucosal tissue provides a unique cell growth substrate that promotes the attachment and proliferation of cells.
It has been reported that compositions comprising submucosal tissue of the intestine of warm-blooded vertebrates can be used as tissue graft materials in sheet or fluidized form. U.S. Pat. No. 4,902,508 describes tissue graft compositions that are characterized by excellent mechanical properties, including high compliance, a high burst pressure point, and an effective porosity index. These properties allow such compositions to be used for vascular and connective tissue graft constructs. When used in such applications the preferred graft constructs serve as a matrix for the in vivo regrowth of the tissues replaced by the graft constructs. U.S. Pat. No. 5,275,826 describes use of fluidized forms of vertebrate submucosal tissues as injectable or implantable tissue grafts.
The present invention is directed to submucosa tissue graft constructs and a method of enhancing or expanding the functional properties of vertebrate submucosal tissues as an implantable or injectable tissue graft construct. The improved tissue graft constructs are prepared by seeding the submucosal tissue in vitro with preselected or predetermined cell types prior to implanting or injecting the graft construct into the host.